Typically, prior art provides abrasive blasting, to increase surface roughness of the surface to be coated.
Blasting is mainly carried out by dry techniques (using compressed air as a carrier fluid) and wet techniques (using water as a carrier fluid) with abrasive particles of various sizes, e.g. corundum and silicon carbide particles.
Increased roughness is obtained by mechanical removal of material from the surface by the abrasive particles impinging thereon.
As a result of this, when corundum is used, a certain number of particles can penetrate the treated surface, thereby weakening the adhesion of the overlying coating whereas, when using silicon carbide, particles tend to decompose during later treatments or during operation of the blasted part, for example, in the case of gas turbine (rotor or stator) parts, during operation of the turbine, with possible formation of low-melting eutectic compounds of Ni and Si or bubbles produced by the combination of carbon with oxygen to form carbon oxide or dioxide.